Most of us know the definition of a sus chord: it is a dominant chord whose major third is replaced by the perfect fourth a half step higher.
But I encounter lots of musicians who know this definition and can’t seem to make heads or tails of it in practice. Perhaps this post will shed some helpful light.

Look at a very simple ii-V-I cadence in the key of C:(Note that the G7 voicing here is in fact a G9. For those of you new to jazz, it’s a common practice to add upper chord tones to voicings, and to omit the fifth, for the sake of voice leading and overall sound.)

Listening to the chords, the sound of the D7 conveys a stable, consonant soothing sound, whereas the G7 conveys more of a “voyage underway”—a tension that will likely resolve to the C before long.

The transition between the D7 and the G7 amounts to exactly two things: (1) the root moves and (2) the seventh of the D7 resolves down a half step to the third of the G7:

We can divide this transition into a two step process, where first the root movement occurs, then the half step resolution:

As we see, the intermediate step is a sus chord. This gives us a useful way to view sus chords:

A sus chord is midway between the iim7 chord and the V7 chord of a ii-V.

It has the consonant, soothing quality of the ii chord which, unlike the V7, contains perfect fifths (between the root & fifth and the third & seventh) and no tritones (the major third and minor seventh of a dominant chord form a tritone). But it takes on some of the sense of movement that a dominant chord conveys. If a dominant chord feels like a voyage underway, then perhaps a sus chord feels like it is preparing to embark on a voyage. It is no coincidence that the composition in jazz that is most closely associated with sus chords is entitled “
Maiden Voyage
“!

A state of “suspension”

“Sus” stands for “suspended.” In Classical theory, a suspension refers specifically to the fourth—or occasionally the second—that is held over briefly from the previous chord. In classical music and in the Tin Pan Alley jazz standards, sus chords are almost always resolved quickly.
But in modern jazz, suspended cords can last indefinitely without resolution—as is the case in “
Maiden Voyage
“. In such cases, the sus chord conveys a broader sense of “suspension”… almost like a feeling of suspension of gravity or suspension of time… as though harmonic forces continue to be steadily at work, but they are not resulting in any change. Once again, the nautical metaphor seems perfect: when you’re out on the ocean, you may know that you are moving forward, and still you may have no sense of forward progress at all, judging by your proximity to the landmarks you see.

A sus chord is a “two chord” over the root of its corresponding “five chord”.

That is to say, D7/G = G7sus. Any voicing for a minor seventh chord is a voicing for a sus chord a perfect fifth lower. In fact, whether a band plays a D7 or a G7sus is entirely up to one musician: the bass player. Anything anyone else plays is the same either way. That gives us a simple answer for how to improvise over a sus chord:

Improvise over a sus chord exactly how you would over a minor seventh chord a fourth lower.

We can see that, case by case, any scale choice for D7 is a great scale choice for G7sus:

Observe also that the chord tones of D11 (1, 3, 5, 7, 9, 11) are in fact the 5, 7, 9, 4, 13 and root of G13sus, respectively. Not only do the proper scales coincide between D7 and G7sus but, in fact, the important notes do as well—so if you emphasize the chord tones of a D7, the results sound great over G7sus. Accordingly, any bebop line you might play that targets chord tones of D7 (or D9 or D11) will sound great over G7sus (or G9sus or G13sus). For example:

Flattening the Ninth

What can we say about the sus9 chord, the darker version of the sus chord? Just as we viewed the Gsus chord as midway between the two and the five chord in a ii-V progression, we can view the G79sus as midway between the two chord and the five chord in a minor ii-V progression:

Playing the third over a sus chord

We’ve all learned at some point that over normal dominant chords, the fourth is an “avoid note”—meaning that it’s fine to use it as a passing note, but we’d better not sit on for any appreciable duration. For example, it doesn’t work to use the 11 in a dominant voicing:

However, we absolutely CAN use the third in a sus voicing. It’s a beautiful sound, akin to the D7(add 6) but over a G root: D7(add 6)/G = G7sus(add 3):

Accordingly, the major third is not an avoid note over sus chords. We can use it to great effect in our improvisations.

Excellent question, Richard. The chord I spelled out is a voicing of a G7. And you’re right, it’s also a G9, which is just a more specific way of referring to it. G9#11, G13b9 G7alt… they’re all instances of G7 chords, and you might play any of them when you see a G7 written in a jazz chart, depending on the context.

I wouldn’t say it’s “also” a G9, it is a G9! Which is a type of G7 chord, sure, but still. Small point really and it’s a good article but I reckon it might confuse some people, better to specify exactly what chord you’re showing especially considering that you do utilize the presence of the 9 later on when you flatten it.

This also seemed confusing to me at first, that is until I did some more research and determined that in Jazz the 9th is usually added to suspended chords (1 4 5 7 9) . This has something to do with sus 4 and sus 2 chords being inversions of each other. I am still confused about the omission of the 5th in the voicing used but this at least accounts for the use of the 9th being assumed in the G7 chord. This would be obvious to someone who is fluent in, and used to paying jazz but not to an amateur like myself or others who I’m sure clicked on this article having little to no idea what a sus chord was.

Well, the bottom four notes work fine for me – a sus-add-3 chord with a 9. (I think: fifth mode of the harmonic minor.) And the top six notes (removing just the bottom note) form an altered voicing. But I can’t really hear the 4, 3 and 9 as coexisting in any agreeable or useful way. Anyone else want to chime in?

Finally a clear explanation, been looking for one on the theory behind it all and couldn’t for the life of me find any, couldn’t find any voicings either. Found information on using them as subs but this very clearly explains how and why they work as a sub for the ii or the ii V , this is how more theory SHOULD be taught instead of “learn this in all 12 keys and use it here”. Very much appreciated

I found this article very useful and actually made notes in my piano workbook which I refer to quite often during practicing. It would have been even more helpful however if an audio example of how it is used in a song was included. Nevertheless good article.

Anton. Many thanks for this post. I’m spending time each day playing through and analyzing some tunes in my fake book and I come across a 13 sus chord. (Bob mintzer’s “change of mind” at letter “B”). If it’s an A13sus isn’t the 11th acting as a sus already? Why does he specify sus?
Thanks again!

Good question, Danno. In an A13 chord there is not necessarily any 11. You could voice it simply with, say, a root, a seven above that, a third about that, and the thirteen on top. If you have an 11 it is necessarily raised, and if you’re writing a chart and want that played, you’d better write A13(#11). So A13sus, with its natural 4, is in fact an altogether different beast.

Thanks for brining that up, Eyal. I consider any voicing of a G9 a voicing of G7 as well—just that the descriptor G9 is more specific than G7. I mean that in the practical sense that any pianist who played a plain G7 (without 9s, 11s or 13s) every time they saw G7 written on a chart would be fired right away. :)

Thank you. That’s a much clearer definition of sus chords than in Mark Levine’s brilliant The Jazz Piano Book.
Love the definition of the susb9 as the darker version of a sus chord. Am I right in thinking that’s also called a Phrygian chord?

Phrygian is a minor scale. If you say “Phrygian Chord” many people will think susb9. But strictly speaking a Phrygian chord should have a minor third in it, whereas suspended chords should have a major third (if any at all). The more “proper” scale choice for susb9 is the fifth mode of the harmonic minor, which is sometimes called Phrygian Dominant because it’s Phrygian with its third raised. THAT SAID, the phryg. versus susb9 distinction can be moot in practice, because the two chords are indistinguishable if, as is often the case, you don’t include any third in the voicing. (Whew! I hope that makes sense.) Glad you enjoyed the post!

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NEWS FLASH!

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NEWS FLASH!

I'm proud to announce that the Random Roots app is now available on the App Store for iPhone/iPad. It's the culmination of a year's work, and I feel it's a game changer for players looking to deepen their musicianship and increase the efficiency and effectiveness of their practice.